There are many techniques for embedding auxiliary information within original data, also known as watermarking or steganography. The original data consists of perceivable media, such as audio, video, stills, etc. It is usually desirable for the embedded data to be non-perceivable, but some content degradation may be okay for some configurations. Several good algorithms have increased the embedded data's ability to resist tampering and removal. One current use of embedded data in media is to include copy management information within the embedded data. Unfortunately, with copy management schemes presented in the prior art, if embedded copy management information is removed the original data is susceptible to illegal distribution.
Embedded data techniques are susceptible to removal of auxiliary information for either of the following reasons. First, the very nature of embedded data is incompatible with bit-rate reducing (a.k.a. compression) schemes, which remove the non-perceivable aspects of the data such as done with MPEG compression. Since a key feature of any embedded data is the fact that it is non-perceivable, compression schemes will act to remove the embedded data. Even if the embedded data is designed to survive the current compression technology, the next generation technology will probably remove it. Bit-rate compression schemes are very important in the digital distribution of media, and receiving much research. Second, noise reduction techniques will be able to remove embedded data. Noise reduction techniques are a hot topic, and used to restore old recordings. Since most non-perceivable embedded data is similar to noise, it will be removed by these noise reduction techniques. Again, even if the embedded data is designed to survive the current restoration technology, the next generation technology will probably remove it.